EFFECT OF INHIBITION OF HEPATIC FATTY-ACID OXIDATION ON METABOLIC ANDHORMONAL RESPONSES TO EXERCISE IN RATS

The purpose of the present study was to assess the effects of 2-mercap toacetate (MA), an inhibitor of hepatic fatty acid oxidation, on the m etabolic and pancreatic hormone responses to a prolonged (3h) swimming exercise. All rats were first adrenodemedullated and were either subm itted for 3 weeks to a normal (5% fat) or a medium-fat diet (MF; 18% f at). After being submitted to an exercise swimming habituation program me for one week, rats under both dietary conditions were either inject ed with a bolus dose of MA (600 mu mol/kg; ip) or with a saline soluti on. MA and saline injected rats were either sacrificed after a 3-h swi mming exercise or after a 3-h resting period. Administration of MA was associated with a lower level of beta-hydroxybutyrate after exercise in rats fed the MF diet, higher resting and exercising blood glucose l evels in rats fed the MF diet, and higher resting and exercising level s of hepatic glycogen in rats fed a normal diet. There were, however, no significant effects of MA on free fatty acid, insulin, glucagon, ep inephrine, and norepinephrine concentrations in both dietary condition s either at rest or after exercise. Therefore, the present data do not provide any evidence that the administration of MA, an inhibitor of h epatic fatty acid oxidation, influences the pancreatic hormonal respon se to exercise. There was also no evidence of a lowering effect of MA on blood glucose levels during exercise.